Hydrocarbon manufacturing system

Abstract

This technology provides a new way to reduce the amount of fossil fuel-derived materials contained in the raw materials used to produce hydrocarbons. [Solution] The reverse shift reactor 12 produces carbon monoxide using carbon dioxide contained in the raw material gas. The Fischer-Tropsch (FT) reactor 14 produces hydrocarbons using hydrogen and carbon monoxide contained in the raw material gas. The separator separates the hydrocarbon gas from the hydrocarbons produced in the FT reactor 14. The boiler 24 burns the hydrocarbon gas. The preheater 26 is located upstream of the reverse shift reactor 12 and heats the raw material gas with the combustion exhaust gas generated in the boiler 24. The raw material gas contains hydrogen produced by the electrolysis of water using renewable energy.

Description

Technical Field

[0001] The present invention relates to a technique for producing hydrocarbons.

Background Art

[0002] As a method for effectively utilizing carbon dioxide contained in exhaust gas or the like, producing a liquid hydrocarbon having a high energy density from carbon dioxide and hydrogen in the presence of a catalyst has been studied (for example, Patent Document 1). Further, as a method for producing a hydrocarbon using hydrogen and carbon monoxide, the Fischer-Tropsch process (hereinafter, appropriately referred to as the "FT process") is known (see Non-Patent Document 1).

[0003] Also, the production of liquid fuels by GTL (Gas to Liquid) using natural gas as a raw material is known (see Patent Document 2). The production of liquid fuels by GTL includes a reforming step of producing hydrogen and carbon monoxide from natural gas and a synthesis step by the FT process of producing higher paraffins using synthesis gas composed of hydrogen and carbon monoxide as a raw material.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Non-Patent Documents

[0005]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In recent years, reducing carbon dioxide emissions from various economic activities has become a major challenge. Therefore, there is a need to minimize the use of fossil fuels such as natural gas and coal as fuels in hydrocarbon production.

[0007] This invention has been made in view of these circumstances, and one of its exemplary objectives is to provide a new technology for reducing fossil fuel-derived materials contained in raw materials used to produce hydrocarbons. [Means for solving the problem]

[0008] To solve the above problems, a hydrocarbon production system according to one aspect of the present invention comprises a reverse shift reactor that produces carbon monoxide using carbon dioxide contained in a raw material gas, a Fischer-Tropsch (FT) reactor that produces hydrocarbons using hydrogen and carbon monoxide contained in a raw material gas, a separator that separates hydrocarbon gas from the hydrocarbons produced in the FT reactor, a boiler that burns the hydrocarbon gas, and a preheater located upstream of the reverse shift reactor that raises the temperature of the raw material gas with combustion exhaust gas generated in the boiler, wherein the raw material gas contains hydrogen produced by the electrolysis of water using renewable energy. [Effects of the Invention]

[0009] According to one aspect of the present invention, it is possible to reduce the amount of fossil fuel-derived materials contained in the raw materials used to produce hydrocarbons. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram showing the outline of the process flow including the hydrocarbon production method according to this embodiment. [Modes for carrying out the invention]

[0011] First, the embodiments of the present invention will be listed. A hydrocarbon production method according to one embodiment of the present invention includes a first production step of producing carbon monoxide using carbon dioxide contained in a raw material gas, and a second production step of producing hydrocarbons using hydrogen and carbon monoxide contained in a raw material gas. The raw material gas contains at least one of carbon dioxide, carbon monoxide, and hydrogen that is not derived from fossil fuels.

[0012] According to this embodiment, it is possible to reduce at least one of carbon dioxide, carbon monoxide, and hydrogen derived from fossil fuels contained in the raw material gas used in the production of hydrocarbons.

[0013] The raw material gas may contain unreacted gas produced in the first or second manufacturing process. Unreacted gases include, for example, carbon dioxide, carbon monoxide, and hydrogen. This improves the utilization efficiency of the raw material gas in the first or second manufacturing process.

[0014] The raw material gas may include hydrogen produced by the electrolysis of water using renewable energy. This allows for the generation of hydrogen while suppressing carbon dioxide emissions.

[0015] The raw material gas may contain carbon dioxide recovered from the atmosphere. This is expected to reduce carbon dioxide in the atmosphere.

[0016] The raw material gas may include carbon dioxide recovered from combustion exhaust gases emitted from thermal power plants, chemical plants, etc. This is expected to reduce carbon dioxide in the atmosphere.

[0017] The process may further include a hydrocarbon gas separation step for separating hydrocarbon gases with four or fewer carbon atoms from hydrocarbons produced in the second manufacturing step, a combustion step for burning the hydrocarbon gases, and a heating step for heating the raw material gas with the combustion exhaust gas generated in the combustion step. The raw material gas may contain carbon dioxide recovered from the combustion exhaust gas. This reduces the amount of carbon dioxide released into the atmosphere. It also reduces the consumption of fossil fuels used to obtain the raw materials.

[0018] The first production process may produce carbon monoxide by the reverse water gas shift (RWGS) reaction.

[0019] The first production process may produce carbon monoxide by electrolytic reduction.

[0020] The second production process may produce hydrocarbons by a reaction according to the Fischer-Tropsch process.

[0021] A recycle gas separation step of separating at least one of carbon dioxide, carbon monoxide, and hydrogen contained in the gas discharged in the second production process as a recycle gas, and a mixing step of mixing the separated recycle gas with the raw material gas used in the first production process may be further included. Thereby, the utilization efficiency of the raw material gas in the first production process or the second production process can be improved.

[0022] At least one of the hydrocarbon gas separation step and the recycle gas separation step may separate the target object by at least any one method of a membrane separation method, a pressure swing adsorption method, or a thermal swing adsorption method.

[0023] The first production process or the second production process may include a reaction that generates water. The water generated in the reaction may be used as a raw material for electrolysis.

[0024] In addition, any combination of the above components, and those obtained by converting the expression of the present invention between a method, an apparatus, a system, etc. are also effective as aspects of the present invention. Also, those obtained by appropriately combining the above-described elements may be included in the scope of the invention for which patent protection is sought by this patent application.

[0025] The present invention will be described below with reference to the drawings, based on preferred embodiments. The embodiments are illustrative and not limiting, and not all features or combinations thereof described in the embodiments are necessarily essential to the invention. The same or equivalent components, members, and processes shown in each drawing are denoted by the same reference numerals, and redundant explanations are omitted as appropriate. Furthermore, the scale and shape of each part shown in each drawing are set for convenience to facilitate explanation and are not to be interpreted restrictively unless otherwise specified. Also, even for the same component, the scale, etc., may differ slightly between drawings. Furthermore, when terms such as "first," "second," etc. are used in this specification or claims, unless otherwise specified, they do not represent any order or importance, but are used to distinguish one configuration from another.

[0026] Figure 1 is a schematic diagram showing the process flow including the hydrocarbon production method according to this embodiment. First, an example of a catalyst system for producing hydrocarbons using the reactor according to this embodiment will be described. The catalyst system 10 shown in Figure 1 comprises a reverse shift reactor 12 located upstream, an FT reactor 14 located downstream of the reverse shift reactor 12, and a reactor 16 that houses the reverse shift reactor 12 and the FT reactor 14.

[0027] The reverse shift reactor 12 receives a raw material gas containing hydrogen and carbon dioxide (and carbon monoxide) from the upstream side, and uses the contained reverse shift catalyst to produce carbon monoxide from carbon dioxide through a reverse shift reaction. In other words, the hydrocarbon production method according to this embodiment includes a step (first production step) to produce carbon monoxide using carbon dioxide contained in the raw material gas. Note that the first production step may also produce carbon monoxide by electrolytic reduction.

[0028] The FT reactor 14 receives a gas containing carbon monoxide and hydrogen generated in the reverse shift reactor 12, and uses the contained FT catalyst to produce gaseous or liquid hydrocarbons by a reaction using the FT method. In other words, the hydrocarbon production method according to this embodiment includes a step (second production step) of producing hydrocarbons using hydrogen and carbon monoxide contained in the raw material gas.

[0029] The FT reactor 14 produces gaseous hydrocarbons with 1 to 4 carbon atoms, namely CH4 and C2-C4 components (e.g., methane, ethane, propane, butane), and C5+ components, which are hydrocarbons with 5 or more carbon atoms and are liquid oil components at atmospheric pressure (e.g., linear alkanes with 5 or more carbon atoms). The generated gaseous and liquid components (water and oil) are separated in a gas-liquid separator 18, and if necessary, fractional distillation is performed to extract the desired components. For example, the liquid components separated in the gas-liquid separator 18 are separated into C5+ components and water by an oil-water separator.

[0030] The gaseous components separated in the gas-liquid separator 18 are separated by the separator 19 into gaseous hydrocarbons (C1-C4) and recycled gas containing at least one of unreacted carbon dioxide, carbon monoxide, and hydrogen discharged from the FT reactor 14. The process of separating the gaseous components in the gas-liquid separator 18 and then separating the gaseous hydrocarbons (C1-C4) from these separated gaseous components in the separator 19 corresponds to the hydrocarbon gas separation process. Similarly, the process of separating the gaseous components in the gas-liquid separator 18 and then separating the recycled gas from these gaseous components in the separator 19 corresponds to the recycled gas separation process. In this embodiment, the hydrocarbon gas separation process and the recycled gas separation process are described separately. However, the process of separating hydrocarbons (C1-C4) from a mixed gas of gaseous hydrocarbons (C1-C4) and recycled gas (gaseous components produced in the FT reactor 14) may correspond to the process of separating recycled gas from the mixed gas. Similarly, the process of separating the recycled gas from the mixed gas may correspond to the process of separating hydrocarbons (C1-C4). In this case, the hydrocarbon gas separation process and the recycled gas separation process can be interpreted as a single separation process. The separator 19 may be capable of separating the target substance by at least one of the following methods: membrane separation, pressure fluctuation adsorption, or temperature fluctuation adsorption. The target substance is a hydrocarbon gas with 4 or fewer carbon atoms in the hydrocarbon gas separation process, and a recycled gas in the recycled gas separation process. If the hydrocarbon gas separation process and the recycled gas separation process are carried out in different separators, only one of the two processes may separate the target substance by one of the following methods: membrane separation, pressure fluctuation adsorption, or temperature fluctuation adsorption.

[0031] Next, we will explain the process of obtaining carbon dioxide, carbon monoxide, and hydrogen contained in the raw material gas. The hydrogen supplier 20 shown in Figure 1 generates hydrogen from the supplied water by electrolysis using renewable energy-derived electricity (RE) and supplies it downstream. This allows for the production of hydrogen while suppressing carbon dioxide emissions, and more preferably without emitting carbon dioxide. The carbon dioxide supplier 22a recovers carbon dioxide from the atmosphere by direct air capture (DAC) and supplies it downstream. This is expected to reduce carbon dioxide in the atmosphere. The carbon dioxide supplier 22b separates and recovers carbon dioxide contained in the combustion exhaust gas (described later) by chemical adsorption and supplies it downstream. This reduces the amount of carbon dioxide released into the atmosphere. It also reduces the consumption of fossil fuels used to obtain the raw materials.

[0032] The hydrogen and carbon dioxide supplied from the hydrogen supply unit 20 and the carbon dioxide supply units 22a and 22b are used as raw material gases for the catalyst system 10 located downstream. Furthermore, a confluence channel is provided in the flow path between the hydrogen supply unit 20 and the catalyst system 10 for mixing the recycled gases (carbon dioxide, carbon monoxide, and hydrogen) separated by the separator 19 with the raw material gases (mixing step). In other words, the raw material gases may include the separated recycled gases (unreacted gases). This improves the utilization efficiency of the raw material gases in the catalyst system 10.

[0033] Furthermore, the raw material gas used by the catalyst system 10 will contain at least one of carbon dioxide, carbon monoxide, and hydrogen that are not derived from fossil fuels. In other words, it is possible to reduce the amount of carbon dioxide, carbon monoxide, and hydrogen derived from fossil fuels contained in the raw material gas used to produce hydrocarbons.

[0034] As described above, the gas-liquid separator 18 and separator 19 separate hydrocarbon gases with 4 or fewer carbon atoms from the hydrocarbons produced in the FT reactor 14 (hydrocarbon gas separation step). The separated hydrocarbon gas (e.g., methane) is then burned together with air in the boiler 24 (combustion step), and the high-temperature combustion exhaust gas is sent to the preheater 26. In the preheater 26, heat exchange takes place between the raw material gas, which has been pressurized by the pump 28, and the combustion exhaust gas (heating step). The heated raw material gas is then supplied to the catalyst system 10, where the subsequent reaction takes place. The combustion exhaust gas, which has undergone heat exchange in the preheater 26, is supplied to the carbon dioxide supplier 22b, where carbon dioxide is recovered.

[0035] Furthermore, both the reverse shift reactor 12 and the FT reactor 14 include reactions that produce water. Therefore, the water separated in the gas-liquid separator 18 and the subsequent oil-water separator may be used as raw material for electrolysis in the hydrogen supply unit 20.

[0036] Next, the details of the reverse shift catalyst used in the reverse shift reactor 12 will be described. The reverse shift catalyst may contain metallic copper, copper oxide (CuO), or both. While the copper-based catalyst functions as a catalyst, it contains at least metallic copper. Therefore, the catalyst is reduced before being used in the reaction. The copper-based catalyst before reduction often contains copper oxide.

[0037] The copper content in the copper-based catalyst is preferably 20 to 100% by mass, based on the total mass of the copper-based catalyst, when the amount of copper components contained in the copper-based catalyst is converted to the amount of metallic copper.

[0038] The copper-based catalyst may further contain zinc oxide (ZnO). The inclusion of zinc oxide in the copper-based catalyst allows for more efficient production of liquid hydrocarbons. When the total amount of copper in the copper-based catalyst is converted to the amount of copper oxide, the proportion of zinc oxide is preferably 10-70% by mass, and more preferably 20-50% by mass, based on the total amount of copper oxide and zinc oxide.

[0039] The reverse shift catalyst may contain at least one metal selected from the group consisting of rhodium, platinum, or iron-chromium. The inclusion of these metals allows for more efficient production of carbon monoxide from carbon dioxide contained in the source gas.

[0040] The copper-based catalyst may further contain a carrier that supports the copper component. When the copper-based catalyst contains zinc oxide, the zinc oxide is usually also supported on the carrier. The carrier is preferably alumina, such as γ-alumina. The carrier content in the copper-based catalyst is, for example, 0.5 to 60% by mass, preferably 1 to 50% by mass, and more preferably 1 to 40% by mass, based on the sum of the copper content, zinc oxide content, and carrier (e.g., alumina) content. The copper content here refers to the amount obtained by converting the total amount of copper components contained in the copper-based catalyst into the amount of metallic copper.

[0041] A copper-based catalyst containing copper and zinc oxide can be obtained, for example, by a method comprising the steps of generating a precipitate containing copper and zinc by coprecipitation and calcining the generated precipitate. The precipitate may include, for example, copper and zinc hydroxides, carbonates, or composite salts thereof. A copper-based catalyst containing copper, zinc oxide, and a support can be obtained by generating a precipitate containing copper and zinc from a solution containing a support (e.g., alumina) by coprecipitation.

[0042] The calcined body, which contains copper and zinc oxide and is formed by calcination, may be powdered, and the powder may be further molded to form granular molded bodies. Examples of methods for molding the powder include extrusion molding and tablet molding. A molded body can also be obtained by molding a mixture containing the calcined body powder and carbon black.

[0043] Next, the details of the FT catalyst used in the FT reactor 14 will be described. The FT catalyst is preferably an iron-based catalyst containing an iron component including metallic iron, iron oxide, or both, and at least one additive metal selected from the group consisting of alkali metals or alkaline earth metals. Alternatively, the FT catalyst may be an iron-based catalyst-copper-based catalyst containing a copper component in addition to the iron component. While the iron-based catalyst functions as a catalyst, it usually contains at least metallic iron. Therefore, the catalyst is usually subjected to a reduction treatment before being used in the reaction. The iron-based catalyst before reduction treatment usually contains iron oxide (e.g., Fe3O4 or Fe2O3).

[0044] The iron content in the iron-based catalyst is preferably 5 to 100% by mass, based on the total mass of the iron-based catalyst, when the total amount of iron components contained in the iron-based catalyst is converted to the amount of iron oxide.

[0045] The additive metals include one or more arbitrarily selected from alkali metals. For example, it is preferable that the additive metals include at least one selected from the group consisting of sodium, potassium, and cesium. Of course, there may be two or more additive metals. By including sodium, potassium, or cesium as additive metals, the liquid hydrocarbon can be produced more efficiently.

[0046] The content of the additive metal in the iron-based catalyst is preferably 0.2 to 40% by mass, and more preferably 0.5 to 20% by mass, based on the amount of the portion of the iron-based catalyst other than the additive metal. When the additive metal contains sodium, the sodium content in the iron-based catalyst is preferably 0.2 to 20% by mass, and more preferably 0.5 to 10% by mass. When the additive metal contains potassium, the potassium content in the iron-based catalyst is preferably 0.2 to 40% by mass, and more preferably 0.5 to 20% by mass. When the additive metal contains cesium, the cesium content in the iron-based catalyst is preferably 0.2 to 20% by mass, and more preferably 0.5 to 10% by mass. When the content of the additive metal is within the above range, the conversion rate from carbon monoxide to hydrocarbons tends to improve further.

[0047] Iron-based catalysts include, for example, Fe 3+ It can be obtained by a method comprising the steps of: generating a precipitate of trivalent iron hydroxide from an aqueous solution containing; calcining the precipitate to form a powder containing ferric oxide; and mixing the powder with an aqueous solution containing an additive metal, and then drying the aqueous solution containing the additive metal.

[0048] The powder containing ferric oxide may be further molded to form granular molded bodies. Examples of methods for molding the powder include extrusion molding and tablet molding. A molded body can also be obtained by molding a mixture containing the powder of a calcined body and carbon black.

[0049] Each catalyst may be heated while the reaction to produce hydrocarbons from the source gas proceeds. The heating temperature for the reaction is, for example, 200 to 400°C. The source gas may contain only carbon dioxide or carbon monoxide, or it may be a mixed gas containing carbon dioxide and carbon monoxide.

[0050] Although the present invention has been described above with reference to the embodiments described above, the present invention is not limited to the embodiments described above, and the present invention also includes combinations and substitutions of the configurations of the embodiments as appropriate. Furthermore, it is possible to appropriately rearrange the combinations and processing order in the embodiments or to make various design changes and other modifications to the embodiments based on the knowledge of those skilled in the art, and such modified embodiments may also be included in the scope of the present invention. [Industrial applicability]

[0051] This invention can be used in hydrocarbon production methods. [Explanation of Symbols]

[0052] 10 Catalyst system, 12 Reverse shift reactor, 14 FT reactor, 16 Reactor, 18 Gas-liquid separator, 19 Separator, 20 Hydrogen feeder, 22a,22b Carbon dioxide feeder, 24 Boiler, 26 Preheater, 28 Pump.

Claims

1. A reverse shift reactor that produces carbon monoxide using carbon dioxide contained in the raw material gas, A Fischer-Tropsch (FT) reactor for producing hydrocarbons using hydrogen contained in the raw material gas and the carbon monoxide, A first separator for separating hydrocarbon gas from hydrocarbons produced in the FT reactor, A boiler for burning the aforementioned hydrocarbon gas, The reverse shift reactor is positioned upstream of the aforementioned reverse shift reactor and includes a preheater that raises the temperature of the raw material gas with the combustion exhaust gas generated in the boiler, The aforementioned raw material gas contains hydrogen produced by the electrolysis of water using renewable energy. Hydrocarbon production system.

2. The hydrocarbon production system according to claim 1, further comprising a carbon dioxide supplier for recovering carbon dioxide from the combustion exhaust gas and supplying it to the raw material gas.

3. The hydrocarbon production system according to claim 1 or 2, wherein the reverse shift reactor and the FT reactor are integrated.

4. A hydrocarbon production system according to any one of claims 1 to 3, further comprising a hydrogen supply unit that generates hydrogen by electrolysis of water using renewable energy and supplies hydrogen to a raw material gas.

5. The first separator separates the gas component containing the hydrocarbon gas from the hydrocarbon, A hydrocarbon production system according to any one of claims 1 to 4, further comprising a second separator for separating the hydrocarbon gas and a recycled gas containing at least one of carbon dioxide, carbon monoxide, and hydrogen discharged from the FT reactor from the gas components in a single step.

6. The reverse shift reactor and the FT reactor include a reaction that produces water. The first separator further separates the water, A hydrocarbon production system according to claim 1 or 4, wherein the water is used as the raw material for the electrolysis.

7. The reverse shift reactor and the FT reactor include a reaction that produces water. The first separator separates the hydrocarbon and the liquid component containing water from the hydrocarbon gas. The hydrocarbon production system further comprises a third separator for separating the liquid component into the hydrocarbon and the water. A hydrocarbon production system according to claim 1 or 4, wherein the water is used as the raw material for the electrolysis.

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